Fuel system with ecology function

Abstract

A fuel system for an aircraft engine comprises a fuel metering unit and a separate flow divider. The flow divider has an inlet port fluidly connected to the fuel metering unit via a fuel line. A primary and a secondary fuel manifold are fluidly connected to the flow divider. The fuel metering unit and the flow divider have a fuel supply mode in which fuel is allowed to flow in a first direction through the fuel line from the fuel metering unit to the flow divider to feed the primary and secondary fuel manifolds, and an ecology mode in which fuel is allowed to flow in a second direction through the same fuel line from the flow divider towards the fuel metering unit. A same fuel line is thus used as a fuel supply line and an ecology line.

The invention claimed is: 
     
       1. A fuel system for an aircraft engine, comprising:
 a fuel metering unit fluidly connectable to a fuel source of the aircraft engine; 
 a flow divider separate from the fuel metering unit and mountable to the aircraft engine at a location remote from the fuel metering unit, the flow divider having a fuel inlet port and a fuel ecology outlet port; 
 a fuel line fluidly connecting the fuel metering unit to the flow divider, the fuel line including a conduit segment extending from the fuel metering unit to the flow divider, the conduit segment fluidly connected to both the fuel inlet port and the fuel ecology outlet port; 
 a flow restrictor between the fuel ecology outlet port and the conduit segment: 
 a primary and a secondary fuel manifold selectively fluidly connectable to the fuel inlet port and the fuel ecology outlet port of the flow divider; 
 wherein the fuel metering unit and the flow divider have a fuel supply mode in which fuel is allowed to flow in a first direction through the conduit segment of the fuel line from the fuel metering unit to the fuel inlet port of the flow divider to feed the primary and secondary fuel manifolds, and an ecology mode in which the fuel is allowed to flow in a second direction opposite to the first direction through the conduit segment of the fuel line from the fuel ecology outlet port of the flow divider to the fuel metering unit, and 
 wherein the flow restrictor is operable to block fuel flow in the first direction from the conduit segment to the fuel ecology outlet port of the flow divider and allow the fuel flow in the second direction from the fuel ecology outlet port to the conduit segment of the fuel line. 
 
     
     
       2. The fuel system as defined in  claim 1 , wherein the fuel ecology outlet port is fluidly connected to the primary and secondary fuel manifolds when the flow divider is in the ecology mode. 
     
     
       3. The fuel system as defined in  claim 2 , wherein the flow restrictor includes a check valve. 
     
     
       4. The fuel system as defined in  claim 1 , wherein the fuel metering unit has an ecology ejector, the ecology ejector having a suction inlet port selectively connectable in flow communication to the conduit segment of the fuel line to withdraw the fuel from the primary and secondary fuel manifolds. 
     
     
       5. The fuel system as defined in  claim 4 , wherein the fuel metering unit further comprises a discharge pressurizing valve, the ecology ejector selectively connectable to the conduit segment of the fuel line via the discharge pressurizing valve. 
     
     
       6. The fuel system as defined in  claim 5 , wherein the discharge pressurizing valve has an ecology outlet port selectively fluidly connectable to the conduit segment of the fuel line. 
     
     
       7. The fuel system as defined in  claim 5 , wherein the discharge pressurizing valve has an inlet port fluidly connectable to the fuel source, an ecology outlet port fluidly connected to the suction inlet port of the ecology ejector, and an inlet/outlet port selectively connectable in flow communication via the conduit segment to either one of the fuel inlet port or the fuel ecology outlet port. 
     
     
       8. The fuel system as defined in  claim 1 ,
 wherein the fuel metering unit includes a discharge pressurizing valve having an inlet port fluidly connectable to the fuel source, an ecology outlet port fluidly connected to a suction inlet port of an ecology ejector, and an inlet/outlet port selectively connectable in flow communication to either one of the fuel inlet port or the fuel ecology outlet port; and 
 wherein the conduit segment extends from the inlet/outlet port of the discharge pressurizing valve to the fuel inlet port of the flow divider, the fuel ecology outlet port of the flow divider fluidly connected to the suction inlet port of the ecology ejector via the flow restrictor, the conduit segment, and the discharge pressurizing valve. 
 
     
     
       9. The fuel system as defined in  claim 8 , wherein the flow restrictor is a check valve mounted between the conduit segment of the fuel line and the fuel ecology outlet port of the flow divider. 
     
     
       10. The fuel system as defined in  claim 9 , wherein the check valve is configured to block the fuel flow from the conduit segment of the fuel line to the fuel ecology outlet port. 
     
     
       11. The fuel system as defined in  claim 8 , wherein the flow restrictor is a passive flow restrictor. 
     
     
       12. The fuel system as defined in  claim 8 , wherein the discharge pressurizing valve is a 3-way, 2-position valve having a first position in which the inlet port of the discharge pressurizing valve is fluidly connected to the inlet/outlet port and the ecology outlet port of the discharge pressurizing valve is closed, and a second position in which the inlet port of the discharge pressurizing valve is closed and the inlet/outlet port is fluidly connected to the ecology outlet port of the discharge pressurizing valve. 
     
     
       13. The fuel system as defined in  claim 8 , wherein the flow divider includes a 4-way, 2-position valve having a third position in which the fuel inlet port of the flow divider is fluidly connected to the primary and secondary fuel manifolds and the fuel ecology outlet port of the flow divider is closed, and a fourth position in which the fuel inlet port of the flow divider is closed and the fuel ecology outlet port is fluidly connected to the primary and secondary fuel manifolds. 
     
     
       14. The fuel system as defined in  claim 8 , wherein the discharge pressurizing valve has a first position in which the inlet port is fluidly connected to the inlet/outlet port while the ecology outlet port is closed, and a second position in which the inlet port is closed and the inlet/outlet port is fluidly connected to the ecology outlet port, wherein the flow divider has a third position in which the fuel inlet port is fluidly connected to the primary and secondary fuel manifolds while the fuel ecology outlet port is closed, and a fourth position in which the fuel inlet port is closed while the fuel ecology outlet port is fluidly connected to the primary and secondary fuel manifolds, wherein the discharge pressurizing valve is in the first position when the flow divider is in the third position, and wherein the discharge pressurizing valve is in the second position when the flow divider is in the fourth position. 
     
     
       15. The fuel system as defined in  claim 8 , wherein the fuel line is an external fuel line configured to be mounted outside of the aircraft engine. 
     
     
       16. The fuel system as defined in  claim 8 , wherein the flow restrictor is a tesla valve. 
     
     
       17. The fuel system as defined in  claim 8 , wherein the flow divider is positioned adjacent to the primary and secondary fuel manifolds.